Deep Injection of Waste Water in the Western Canada Sedimentary Basin

Abstract

Injection of wastes into the deep subsurface has become a contentious issue, particularly in emerging regions of oil and gas production. Experience in other regions suggests that injection is an effective waste management practice and that widespread environmental damage is unlikely. Over the past several decades, 23 km(3) of water has been injected into the Western Canada Sedimentary Basin (WCSB). The oil and gas industry has injected most of this water but large amounts of injection are associated with mining activities. The amount of water injected into this basin during the past century is 2 to 3 orders magnitude greater than natural recharge to deep formations in the WCSB. Despite this large-scale disturbance to the hydrogeological system, there have been few documented cases of environmental problems related to injection wells. Deep injection of waste appears to be a low risk activity based on this experience but monitoring efforts are insufficient to make definitive statements. Serious uncharacterized legacy issues could be present. Initiating more comprehensive monitoring and research programs on the effects of injection in the WCSB could provide insight into the risks associated with injection in less developed sedimentary basins.

Myths and Facts on Wastewater Injection, Hydraulic Fracturing, Enhanced Oil Recovery, and Induced Seismicity

“…The wells in which these fluids are disposed are known as wastewater wells or salt-water disposal wells. Underground disposal of wastewater has a lengthy history because it is typically considered an economic and safe option (Ferguson, 2015).…”

Conventional Oil—The Forgotten Part of the Water‐Energy Nexus

“…The overall amount of water produced and injected in these environments is not balanced according to available data (Figure ). The WCSB has an excess of 3.0 × 10 9 m 3 of water within the basin injected by wells equivalent to EPA Class II wells, with the majority of this water used for EOR (Ferguson ). The presence of excess water in the WCSB is in approximate agreement with annual freshwater use by the oil and gas industry in Alberta for EOR and in situ oil sands recovery projects.…”

“…Injection in Oklahoma between 2000 and 2010 resulted in an excess of 1.32 × 10 9 m 3 of water in the subsurface (Murray ). These excess volumes are attributed to injection of produced waters from other states (Lutz et al ; Gilmore Kevin et al ), as well as fresh and brackish groundwater and surface water for EOR (Murray ; Ferguson ; Scanlon et al ).…”

“…The amount of water injected and produced for conventional and unconventional oil and gas production for (a) various periods and (b) normalized to a per year basis for the Western Canada Sedimentary Basin (WCSB; 1950‐2014) (Ferguson ), Permian Basin (2005‐2015)(Scanlon et al ), states of Oklahoma (OK; 2000‐2010) (Murray ), California (2005‐2015) (State of California Department of Conservation ), and Ohio (2011‐2017) (Shumway et al ), along with the United States total (U.S. total) produced water volume for 2012 (Veil ) and the total volume used for HVHF in the United States (USHF; 2005‐2014) (Kondash and Vengosh ).…”

Subsurface fluid injection and induced seismicity in southeast Saskatchewan

“…of slip on a well-oriented fault. The effective stress, σ' ij , is determined as a function of the 371 stress tensor applied to the rock, σ ij , and the pore pressure, P: caused by a pore pressure change ΔP: (Ferguson, 2015). However, it is worth comparing 419 our study area with others that have experienced much higher levels of induced seismicity 420 from similar levels of oilfield activity.…”